Onde Magnetique Will Wow And Flutter Your Ears

[Scott Campbell] built a cassette-based synthesizer that sounds exactly like everything you’ve heard before. The sound generation comes straight off cassettes, but the brainbox of this synth varies the volume and pitch. It’s called the Onde Magnetique, and it is what you would get if you combined a Mellotron and Ondes Martenot.

The key component for the Onde Magnetique is a Sony cassette recorder that conveniently and inexplicably comes with a ‘tape speed input’ mini jack. By varying the voltage sent to this input jack, the speed of the tape, and thus the pitch of the sound being played, is changed. Build a box with a touch-sensitive button for volume, and a few tact switches for different speeds, and you have an electromechanical bastard child of a Mellotron and an Ondes Martenot.

By itself, the Onde Magnetique produces no sound – it only controls the pitch and volume of whatever is on the cassette. [Scott] produced a few single-note cassettes for his instrument, with ‘voice patches’ including a flute, choir, and a synth. With the CV and Gate input, these sounds can be sequenced with outboard gear, producing the wonderful sounds heard in the video after the break.

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Light Up Component Bins and a Manual Pick and Place

[Mike] makes some very niche musical instruments, and the production volume he’s looking at means there isn’t a need to farm out his assembly. This means doing everything by hand, including the annoying task of picking resistors and other components out of bins. After searching for a way to speed up his assembly process, he came up with the Stuffomatic, a device that locates the correct component at the press of a button.

The normal way of grabbing a part when assembling is reading the reference on the board, cross referencing the value on the BOM, and digging the correct part out of the bin. To speed this up, [Mike] put LEDs in each of the part bins, connected to a Teensy 2.0 that has the BOM stored in memory. Clicking a foot switch looks up the next component and lights up the LED in the associated part bin.

[Mike] says this invention has speeded up his assembly time by about 30%, a significant amount if you’re looking at hours to assemble one unit.

If you’re wondering exactly what [Mike] is assembling, check this out. It’s heavily inspired by the Ondes Martenot, an electronic musical instrument that’s about as old as the theremin, but a million times cooler. Video sample below.

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The Ondes Martenot; Better than a Theremin


[Ville] loves the sound of an ondes martenot and decided to build his own. No, it’s not made of vacuum tubes like a 1920s original, this one is made out of a cheap, off-the-shelf analog synth and just a few extra parts.

The ondes martenot is a theremin-like musical instrument; instead of waving your hands around aerials on the theremin, the ondes uses a small ring attached to the player’s finger on a wire loop and a volume lever. The ondes isn’t a common instrument by any means, but Radiohead uses one several in any event.

[Ville] began his build by taking a small, cheap, and new Korg Monotron analog ribbon synth, cracking it open, and reading the schematics. A 100k multiturn pot was wired into the monotron and fastened to a printed paper keyboard with a system of pulleys and a small metal ring. With the multiturn pot wired into the pitch input on the monotron, [Ville] had a semi-accurate and very functional ondes martenot replica.

You can hear [Ville]’s ondes in action after the break. It’s a little rough starting out, but by the time he’s looping multiple phrases it really does sound wonderful.

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